1,721,039 research outputs found
Cl constrains on shallow plumbing system and pre-eruptive conditions of the Phlegrean Fields
No full textMagma degassing and eruption dynamics of the Avellino pumice Plinian eruption of Somma–Vesuvius (Italy). Comparison with the Pompeii eruption.
No full textChlorine as a geobarometer tool: Application to the explosive eruptions of the Volcanic Campanian District (Mount Somma-Vesuvius, Phlegrean Fields, Ischia)
No full textMagma reservoir growth and ground deformation preceding the 79 CE Plinian eruption of Vesuvius
Full text linkThe 79 CE eruption of Vesuvius is the first documented Plinian eruption, also famous for the archaeological ruins of Pompeii and Herculaneum. Although much is known regarding the eruption dynamics and magma reservoir, little is known about the reservoir shape and growth, and related ground deformation. Numerical modelling by Finite Element Method was carried out, aimed at simulating the reservoir growth and ground deformation with respect to the reservoir shape (prolate, spherical, oblate) and magma overpressure. The modelling was tuned with volcanological, petrological and paleoenvironmental ground deformation constraints. Results indicate that the highest magma overpressure is achieved considering a prolate reservoir, making it as the most likely shape that led to eruption. Similar deformations but lower overpressures are obtained considering spherical and oblate reservoirs. These results demonstrate that ground deformation may not be indicative of eruption probability, style/size, and this has direct implications on surveillance at active explosive volcanoes
Halogen elements in magmas, from the tracing of storage conditions to the eruptive fluxes
No full textLes éléments halogènes sont caractérisés par une configuration électronique S2P5 qui leur confère une très forte électronégativité leur permettant de former des ions halogénures très réactifs (X-, où X est un élément halogène). De par leur comportement volatil et incompatible dans la plupart des minéraux cristallisant dans les réservoirs magmatiques, leur concentration augmente dans la phase liquide résiduelle lors de la cristallisation fractionnée. Lorsque le magma remonte vers la surface, la solubilité des éléments volatils diminuant (parmi lesquels les éléments halogènes), ils s’exsolvent du magma sous forme de gaz. Les gaz émis lors des éruptions pliniennes sont propulsés à plusieurs kilomètres d’altitude et, selon l’importance de l’éruption, peuvent parvenir dans la stratosphère. Une fois injectés dans la stratosphère, les éléments halogènes ont un temps de résidence qui varie selon l’élément et le composé qu’il forme, et qui peut atteindre plusieurs années. Ils y déstabilisent les équilibres chimiques et provoquent la destruction de l’ozone stratosphérique. La méthode utilisée durant cette thèse consiste en une estimation du volume total d’un élément volatil donné émis lors d’une éruption, par la différence de concentration de l’élément dans le magma avant et après éruption. Le dégazage correspond à la différence de concentration de l’élément avant et après éruption. Cette méthode présente le double intérêt de permettre la mesure de la concentration totale de l’élément dans le magma, de manière non spécifique, et de ne pas requérir d’observation directe au moment de l’éruption.Halogen elements have a characteristic S2P5 electronic configuration which gives them a very high electronegativity. Hence, they form highly reactive halide ions (X-, where X is a halogen element). Because of their volatile and incompatible behaviour in most of the minerals crystallising in magma reservoirs, their concentration increases in the residual liquid phase during fractional crystallisation. As the magma rises to the surface, the solubility of the volatile elements (including the halogen elements) decreases and they exsolve from the magma as gases. The gases emitted during plinian eruptions are propelled several kilometres into the atmosphere and, depending on the size of the eruption, they may reach the stratosphere. Once the halogen elements injected into the stratosphere, their residence time depend on the element and the compound it forms, and can reach several years. The halogen elements destabilise chemical balances in the stratosphere and cause the destruction of stratospheric ozone. The method used in this thesis consists in an estimate of the total volume of a given volatile element that is emitted during an eruption, from the difference in concentration of the element in the magma before and after eruption. The degassing thus corresponds to the difference in concentration of the element before and after eruption. This method has the double advantage of allowing to measure the total concentration of the element in the magma, in a non-specific way, and of not requiring direct observation at the time of the eruption
Halogen diffusion in magmatic systems: Our current state of knowledge
No full textInternational audienc
Data for: What creates the arc sulfur isotopic signature? Insights from sulfur isotopes from mantle wedge to crustal magma reservoirs beneath Bezymianny volcano, Kamchatka
No full textSupplementary data for the manuscript by Davydova V.O., Shcherbakov V.D., Balcone-Boissard H., Deloule E. and Yapascurt V.O. "What creates the arc sulfur isotopic signature? Insights from sulfur isotopes from mantle wedge to crustal magma reservoirs beneath Bezymianny volcano, Kamchatka", submitted to Geochimica et Cosmochimica ActaTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
Magma plumbing system architecture and dynamics, a crystal perspective
No full textInternational audienceMagmas on Earth are more or less crystallized and they may display a wide range of crystal type, sometimes referred as the crystal cargo. First, crystals may entrap silicate melt from magma reservoirs as melt inclusions, acting as witness of magma storage conditions at the time of their entrapment. By analyzing them carefully we can retrieve information on magma pounding zones and thus about the architecture of magma plumbing system through time as well as magma ascent path and degassing. Crystals act also as key archives of magmatic processes, enabling a deeper understanding of the physico-chemical conditions during magma evolution and its pathways through Earth's crust. In particular, crystals in disequilibrium emphasized have a relevant role as a witness to trace crystallization conditions and magmatic dynamics. As this session aims to explore the reconstruction of magmatic history through crystal studies, I will present recent results on crystal analyses, particularly linking melt inclusion composition, and crystal textures and compositions to specific processes such as fractionation, recharge, mixing, assimilation, and degassing. In addition, the use of crystals as chronometers, particularly through diffusion chronometry, provides valuable insights into the timescales of different magmatic processes, contributing to volcanic monitoring and eruption forecasting. The rise of diffusive chronometry has thus made it possible to better constrain the dynamics of magmatic systems, with its advantages and limitations. Given this approach, we can now move to interdisciplinary approaches integrating petrological and volcanological investigations and human and social science researches
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